This invention relates to motor control centers having compartmentalized cabinets for receiving removable control units which are inserted or withdrawn through open fronts of the respective compartments. More particularly, this invention relates to a plug-in connector module carried by the removable control unit and having electrical connectors which stab onto bus bars of the motor control center upon insertion of the removable control unit into the respective compartment to electrically engage the bus bars and thereby connect control apparatus of the removable control unit to a source of electrical power.
Removable control units of the aforedescribed type have customarily had stab-on or plug-in connector modules attached to the rear surface of the removable control unit. These modules serve to mount electrical clip connectors which engage with the bus bars. In view of misalignment situations between the bar bars and clip connectors, the latter are commonly afforded limited pivotal movement within the module and the electrical connection between the clip connector and the control apparatus of the unit is made by flexible conductor such as a stranded wire. The stranded wire is routed from the rear-mounted connector through an opening in the rear panel of the removable control unit to the terminals of a front-mounted control device of the removable control unit. Wires routed along the rear surface of the panel are subject to damage, primarily from control device mounting screws extending through the panel. Stranded wire has an economic disadvantage in that one end thereof must be provided with a crimped or pressure connector and the opposite end is either provided with a similar connector or is brazed or welded directly to the stab-on connector clips. Moreover, where the ampere rating for the control device is high, the wire thickness increases. Thick wires are difficult to bend, require additional space due to larger bending radii, and lose the desired flexibility for pivotal movement of the clip connectors. In some instances, additional care must be taken to line the opening in the rear panel of the removable control unit with an insulating bushing or the like so that insulation on wires extending therethrough is not damaged by sharp edges of the panel opening.